Aichi virus inactivation by heat in 2-ml glass vials

Abstract

Aichi virus (AiV) that results in gastroenteritis worldwide, is spread through contaminated shellfish and water. The resistance/tolerance of AiV to common inactivation processes along with the absence of commercially available vaccines makes it necessary to study its thermal inactivation kinetics. This research evaluated the heat inactivation of AiV in cell-culture media using 2-ml sterile glass vials by the linear and Weibull models. Heat treatments of AiV titers of 7 log plaque forming units (PFU)/ml were conducted thrice in a water-bath at 50, 54, and 58 °C for up to 90 min. Plaque assays for each dilution in duplicate were used to determine infectious virus titers. Linear model D-values for AiV at 50 ± 1 °C (± = standard error) (come-up time = 68 s), 54 ± 0.7 °C (130 s), and 58 ± 0.6°C (251 s) were 43.3 ± 4.23 (R² = 0.40, RMSE = 0.56), 5.69 ± 0.28 (R² = 0.80, RMSE = 0.43), and 1.20 ± 0.63 min (R² = 0.69, RMSE = 0.39), respectively, and the linear model z-value was 5.14 ± 0.39°C (R² = 0.99, RMSE = 0.08). For the same temperatures, the Weibull model t_{d = 1} values were 20.98 ± 8.8 (R² = 0.62, RMSE = 0.46, α (scale parameter) = 2.30, β (shape parameter) = 0.38), 3.84 ± 0.69 (R² = 0.85, RMSE = 0.38, α = 1.08, β = 0.66), and 0.87 ± 0.10 min (R² = 0.80, RMSE = 0.32, α = 0.22, β = 0.61), respectively and the z-value (using T_{d = 1} ) was 5.79 ± 0.22 °C (R² = 1.0, RMSE = 0.03). A better fit was obtained with the Weibull model for log reductions versus time with higher R² and lower RMSE values. Application of AiV inactivation parameters can help reduce the risk of AiV outbreaks.

Keywords: D-value; aichi virus; heat inactivation; z-value.